JPS6350118A - Contact signal input circuit - Google Patents

Abstract

PURPOSE:To generate a power loss caused by a current limiting element, and to make it unnecessary to execute a heat radiation countermeasure, by using a series capacitor as the current limiting element for reducing a circuit current by an AC power source. CONSTITUTION:A series capacitor is used as a current limiting element for reducing a circuit current by an AC power source. That is to say, since this circuit is constituted of a deries capacitor 16 and an equivalent load resistance 19, a current I flowing through an input circuit leads a voltage of an AC power source 2 by a phase angle. Subsequently, a voltage applied to the equivalent load resistance 19 is a resistance load, therefore, it becomes the same phase as the current I, and an effective power is consumed. Also, a voltage applied to the series capacitor 16 is a capacity load, therefore, it lags the current I by 90 deg., and the consumption of the effective power does not occur.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a contact that is used as a condition for control, etc. by inputting the open/closed state of a contact, which represents the internal state of a device to be controlled, using an AC power source. This relates to input circuits.

[Conventional technology]

Figure 4 shows, for example, the 1978 Electrical Calculation Special Edition VOL.

46NO, 11 (P, 27 FIG. 2) shows the conventional contact signal input circuit. Further, FIG. 5 shows an equivalent circuit of a conventional contact signal input circuit, and FIG. 6 shows a vector diagram of a conventional contact signal input circuit (equivalent circuit). In Figs. 4 to 6, fl) is the control device, αυ is the series resistance, @ is the rectifier circuit, 0 is the photocoupler, 0 is the logic circuit, and the symbol is the equivalent load resistance (rectifier circuit + photocoupler), +21 is the AC power supply, (3) is the contact, (*) is the voltage of the AC power supply (vector), (1) is the current flowing through the signal input circuit (vector), (R) is the resistance value of the series resistor, (r
) is the resistance value of the equivalent load resistance (rectifier circuit + photocoupler), (Ω, ) is the voltage (vector) across the series resistor, (*
r) is the voltage (vector) across the equivalent load resistance.

Next, the operation will be explained.

First, consider the case where the contact (3), which is the signal source, is on. In this case, the contact (3) that is on, the AC power supply (2), the series resistance 0υ, the rectifier circuit side, the photocoupler α
A closed circuit is formed by the current, and the circuit current from the AC power source (2) flows through this closed circuit. Since the rectified waveform output from the rectifier circuit flows through the primary side diode of the photocoupler α port, the output transistor on the photocoupler side is turned on. This output transistor is connected to the input terminal of logic circuit 0, and by detecting that this output transistor is on, logic circuit 04) can detect that contact (3), which is the object of detection, is on. can be recognized.

Second, consider the case where contact (3), which is a signal source, is off. In this case, since a closed circuit including the AC power supply (2) is not formed, the output transistor of the photocoupler α terminal is finally turned off. Therefore, in this case, the logic circuit 0
By detecting that this output transistor is in the off state, it is possible to recognize that the contact point (3) to be detected is in the off state.

Next, according to Figures 5 and 6, contact (3) which is the signal source
Let's evaluate the amount of power consumed by the circuit when it is on.

As shown in Figure 5, the series resistance αυ and the equally polarized load resistance 01
are all pure resistances. Therefore, as shown in Figure 6, each voltage (*, 9, *,) can be said to be in the same phase as the current (i).

Therefore, the amount of power P) consumed by the circuit when the contact (3), which is the signal source, is on is as follows.

[Problem that the invention seeks to solve]

Since the conventional contact signal input circuit is configured as described above, when the contact (3) which is the signal source is on, the power (power loss) consumed by the series resistor αυ is I”R Therefore, there were problems such as the need for a large-capacity series resistor and measures against heat generation.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a contact signal input circuit that eliminates series resistance and eliminates power loss and heat generation caused by the series resistance.

[Means for solving problems]

The contact signal input circuit according to the present invention uses a series capacitor as a current limiting element for restricting the circuit current generated by the AC power source.

[Effect]

The contact signal input circuit of this invention uses a series capacitor as a current limiting element to throttle the circuit current from the AC power supply, thereby converting the power consumed by the element into reactive power, thereby reducing the active power loss due to the element and the heat generation of the element. It is something to eliminate.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
2 is an equivalent circuit of the contact signal input circuit according to the present invention, and FIG. 3 is a vector diagram of the contact signal input circuit (equivalent circuit) according to the present invention.

In Figures 1 to 3, tll is a control device, (2) is a rectifier circuit, 0 is a photocoupler, Q4) is a logic circuit, and α
Q is a series capacitor, 0! is equal load resistance (rectifier circuit +
Photocabra), +21 is AC power supply, (3) is contact point,
(*) is the voltage of the AC power supply (vector), (i) is the current flowing through the signal input circuit (vector), (C) is the capacitance of the series capacitor, (r) is the equal load resistance (rectifier circuit + photo (9c) is the voltage (vector) across the series capacitor, (*r) is the voltage (vector) across the equally polarized load resistance, and (ω) is the angular velocity of the AC power supply.

Next, the operation will be explained.

First, consider the case where the contact (3), which is the signal source, is on. In this case, a closed circuit is formed by the turned-on contact (3), the AC power supply B (2), the series capacitor α, the rectifier circuit (2), and the photocoupler 0, and the AC power supply (2)
The circuit current will flow through this closed circuit. Since the rectified waveform output from the rectifier circuit flows through the primary side diode of the photocoupler α, the output transistor of the photocoupler 0 is turned on.

This output transistor is connected to the input terminal of the logic circuit α ship, and by detecting that this output transistor is in the on state, the logic circuit α ship detects that the contact (3) to be detected is in the on state. I can recognize something.

Second, consider the case where the contact (3+), which is the signal source, is off. In this case, a closed circuit including the AC power supply (2) is not formed, so the output transistor of the photocoupler a-to is eventually turned off. Therefore, in this case, the logic circuit α
By detecting that this output transistor is in the off state, it is possible to recognize that the contact (3) to be detected is in the off state.

Next, according to Figures 2 and 3, contact (3) which is the signal source
Let's evaluate the amount of power consumed by the circuit when it is on.

As shown in Fig. 2, the circuit consists of a series capacitor αQ and an equally polarized load resistance O1, so as shown in Fig. 6, the current (i) flowing through the input circuit is the electric field (*) of the AC power supply (2).
), the voltage (*r) applied to the evenly polarized load resistor 091 is in the same phase as the current (i) because it is a resistive load, and effective power is consumed. . Also, since the voltage (*C) applied to the series capacitor αe is a capacitive load, the phase lags the current <i> by 90'', and no active power is consumed (only reactive power is generated).

) Therefore, the amount of power P) consumed by the circuit when the contact (3), which is the signal source, is on is as follows.

〔Effect of the invention〕

As described above, according to the present invention, since a series capacitor is used as a current limiting element to throttle the current of a contact signal input circuit using an AC power supply, there is no power loss due to the current limiting element. The limiting element itself can be made smaller, and there is no need for heat dissipation measures.

[Brief explanation of the drawing]

FIG. 1 is a contact signal input circuit according to the present invention, FIG. 2 is a vector diagram of the contact signal input circuit (equal polarity wII) according to the present invention, Fig. 4 shows a conventional contact signal input circuit, Fig. 5 shows a conventional contact signal input circuit with equal eccentricity (contact meter shape a), and Fig. 6 shows a conventional contact signal input circuit (equal deviation It is a vector diagram of the road). +11 is the control device, (2) is the AC power supply, (3) is the contact (
signal source), Qll is a series resistance, (2) is a rectifier circuit, α
are the photocoupler, 0 is the logic circuit, Q6) is the series capacitor, 0 is the equal load resistance, (*) is the voltage of the AC power supply (vector), (i) is the current flowing through the signal input circuit ( vector), (R) is the resistance value of the series resistor, (r) is the resistance value of the equally polarized load resistor, (V*) is the voltage across the series resistor (vector)
, (*P) is the voltage (vector) across the equally polarized load resistance,
(C) is the capacitance of the series capacitor, (*C) is the voltage (vector) across the series capacitor, (ω) is the angular velocity of the AC power supply, and (P) is the power consumed by the contact signal input circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Masuo Oiwa Figure 1 Figure 2 Figure 3: ItdXlh = 1Irl'1II = 12r Figure 4 Figure 5 Figure 6 Flash 1, Indication of the incident Patent Application No. 194282/1986 3
, Representative of the person making the amendment Moriya Shiki 6, Date of amendment order (date of dispatch) October 28, 1986 6, Brief explanation of drawings in the specification subject to amendment 7, Contents of the amendment in the specification , on page 9, line 8, “Figure 2” was replaced with “Figure 8.”
"Fig." is corrected. that's all

Claims (1)

[Claims] An AC power supply having a contact that turns on or off depending on the state of the controlled device, one terminal of which is connected to one terminal of the contact, and the other terminal connected to the other terminal of the contact. , a capacitor whose one terminal is connected to the other terminal of the AC power supply, a rectifier circuit whose one terminal is connected to the other terminal of the capacitor, and whose positive input terminal is connected to the positive output terminal of the rectifier circuit. A contact signal input circuit comprising: a photocoupler connected to the photocoupler, the negative input terminal of which is connected to the negative output terminal of the rectifier circuit; and a logic circuit that inputs an output signal of the photocoupler.